The operations and maintenance (O&M) of thermal power plants (TPPs) is critical to guarantee that they operate efficiently and without interruption. Adopting effective O&M methods has become essential in the coal-based power generating segment, given the constraints of a shifting fuel mix, flexible operation and tougher environmental and safety requirements. Best O&M practices at TPPs help not only in achieving high levels of performance, but also maintain the health of the power plant equipment. For effective O&M, real-time monitoring of important parameters, predictive and preventive maintenance and condition-based monitoring are gaining traction. Further, machine learning, artificial intelligence and data analytics can offer several benefits.
Power Line takes a look at some of the O&M practices adopted by major central, state and private generating companies (gencos)…
Gencos’ O&M initiatives
NTPC Limited: Cycling of plants, ancillary services requirement, frequent load following and ramping in short range cause stresses due to creep and fatigue loading. For this, one focus area is autoloop control tuning of control systems and advanced control measures, with additional condition monitoring systems. NTPC is implementing one digitalisation package across the company, an advanced analytics and visualisation platform, for integration and consolidation of all the data. It has also awarded another package for real-time diagnostics and an advisory support system that would use advanced pattern recognition technique for early warning for incipient faults, thereby facilitating continuous monitoring of the health and performance of the equipment. The utility has adopted a fatigue monitoring system to monitor the condition of thick wall pressure parts and life of these components. Besides this, NTPC is also looking at robotics and drones, chimney inspections, edge-type inspections, and coal yard mapping, among others. As original equipment manufacturers (OEMs) may move to renewable energy, they may gradually withdraw from manufacturing and may not provide adequate support for spares and services for TPPs. There is a concern regarding balance of plant facilities, namely, coal handling plants, ash handling plants, or aerated bearings where the actual requirement number may not be very high. So, there would be a need to import these high-cost bearings from abroad, with a high purchase lead time. So, on a policy basis, it is imperative to incentivise and develop alternative resources for spares of TPPs, for continued reliable operations.
Mahagenco: Maharashtra State Power Generation Company Limited (Mahagenco) has developed standard operating procedures and an expert team for effective O&M practices. The utility has adopted a three-point programme, which includes efficiency improvement, environment protection for reduced carbon footprint, capacity addition and energy services and consultancy. Notably, a decline in coal quality, which is happening today, affects the boiler and causes erosion and boiler tube leakage. Therefore, Mahagenco now uses washed coal for efficiency improvement. For flexible operations, the utility is in talks with OEMs. Further, it is giving priority to improving reliability, minimising auxiliary power consumption effective utilisation of all resources, and safety of man and machines. For environment protection, it has adopted the 3Rs – reduce, reuse and recycle. The water consumption in Mahagenco’s TPPs is well below limits. The utility uses water from sewage treatment plants at the Koradi and Khaperkheda TPPs and plans to adopt the same at more TPPs are also under way. Moreover, it is working towards upgrading the skills of its employees through courses available at their centres in Nasik and Koradi.
Adani Power: Adani Power has adopted a data-driven approach to O&M since 2012. It has adopted DISHA, a business process transformation initiative focused on power business operations to integrate all its processes in the IT-enabled platform. The objective behind DISHA is to establish sustainable practices in O&M, fuel management, strategic planning and revenue management; management information system and human resource processes of global standards through operating model redesign; and process definition and implementation, including IT enablement. The company has introduced reliability-centred maintenance across all stations. Further, safety remains a major focus area for which it has been working with DuPont to achieve “Zero Harm” through “Project Chetna” at all its stations. It follows stringent key performance indicator (KPI) monitoring on a day-to-day basis. For spare management, the company relies 70-80 per cent on indigenously developed spares since 2015. The company also has an energy network operation centre in Ahmedabad, wherein integrated data is collated and analysed for decision-making.
JSW: Currently, utilities are doing too much maintenance. For example, for turbine overhaul, it is opened every three to five years, while in Europe and the US, these are opened once in 10 years. Further, these regions have adopted online pumping. Similarly, for condensers, these are opened every two to three years. To avoid too much maintenance, utilities should adopt risk-based maintenance. During flexible operations, low load results in more fatigue, for example, as in the case of the Ratnagiri and Vijayanagar TPPs. For this, we have traditionally relied on radiography, but a renewed focus should be placed on non-destructive tests, which can be carried out on selected components. This may include phased array ultrasonic testing or mixing with eddy current to ascertain the damage. Previously, the lube oil systems were drained and lubricants were replaced during each major plant outage or shutdown, but the life of lubricants is 25 years, hence, there needs to be a replacement criterion in place. There is a need to adopt KPI-based maintenance rather than manpower-based maintenance. Although a lot of reverse engineering has been done for metallurgical and mechanical aspects, there is still a long way to go for electrical and electronic aspects. Going forward, turbine cooling, turbine washing and pump cleaning for upper base deposits are required. As per the recent annual report of JSW, during the Covid-19 pandemic, the company demonstrated the capability of remote handling of O&M operations, through a full-fledged set-up of human-machine interface stations at the respective townships of energy plants. This resulted in timely support of operations, delivered remotely during the pandemic period.
The energy landscape is undergoing a major change in the country. As TPPs are preparing for flexible operations, they are transitioning to cyclic operations as against baseload operations. This will lead to faster deterioration of plant components, higher O&M expenses due to the reduced life of components, additional costs owing to an increase in the heat rate and auxiliary power consumption, and an increase in oil consumption on account of frequent starts/stops. Therefore, utilities are required to adopt best-in-class O&M practices to achieve business excellence and ensure long-term economic viability.
To keep the cost of generation low, activity-based budgeting and cost-cutting measures, as well as optimal fuel mixing are required. Root cause analysis, reliability-centred maintenance, multi-year overhaul plans, zero-forced-outage strategies and systematic inventory management are some of the key maintenance procedures being deployed by utilities to improve their O&M practices.
Utilities should aim to reduce start-up time to achieve operational excellence and maximise plant availability and load factors. Overall, the adoption of new and innovative technologies, cost savings and work mechanisation should be prioritised. Capacity building and training could also enable TPPs to improve their O&M. Furthermore, best practices in O&M enable reliability of power plants, help maintain plant safety and availability and enhance asset flexibility, while keeping maintenance costs at a minimum. Going forward, utilities should adopt tailored O&M strategies based on their requirements. n
Based on a panel discussion among Achal Kumar Arora, General Manager, Operation Services-SIIS, NTPC Limited; Abhay Harne, Chief Engineer and Executive Director (additional charge), Mahagenco; Ashesh Padhy, Senior Vice-President, JSW Steel; and Girish Raghuwanshi, Associate Vice-President, Adani Power, at a recent Power Line conference